358 
Mr Fenton , Oxidation in Presence of Iron. 
Oxidation in Presence of Iron. By Henry J. Horstman 
Fenton, M.A., F.R.S. 
[Received 1 March 1902.] 
The remarkable influence which is exerted by traces of iron 
salts in determining and regulating the oxidation of various 
organic substances was first observed by the author in 1876, and 
the observation has since opened up a very wide and fruitful field 
for investigation. Since the researches which have been published 
in this direction extend over a considerable period and have 
appeared in various journals, it has been considered advisable to 
communicate to the Society a brief summary of the work 
together with an account of recent results not hitherto pub- 
lished. 
The function of the iron in these reactions is twofold : in the 
first place it increases the activity of the oxidizing agent to a 
remarkable extent, and secondly it has a selective or regulating 
influence so that certain groups are attacked and others left. 
This second influence may be regarded as the essential and novel 
feature of the actions referred to, oxidations being effected in this 
way which are not possible by any other means; the mere in- 
crease of activity may of course be induced by other agents and 
is not peculiar to iron. 
It has been considered necessary to emphasize this point and 
also to draw attention to the dates of publication, since considerable 
misconceptions with regard to these matters appear to exist. 
[Compare G. Ollendorff, Inaugural Dissertation , Berlin, July 1900, 
ii] 
The first substance investigated in this direction was tartaric 
acid ; it was observed that this acid, or its salts, when treated 
with certain oxidizing agents in presence of ferrous iron gave, on 
addition of caustic alkali, a beautiful violet colour [Chemical 
News, 1876, 33. 190; 1881, 43. 110]. The explanation of this 
effect and the isolation and identification of the active product 
was at first a matter of very considerable difficulty owing to the 
unstable character of the substance in aqueous solution. In 1894 
this product was isolated and proved to be the hitherto missing 
dioxy maleic acid. From this acid a large number of interesting 
derivatives have been obtained, and its decompositions and trans- 
formations afford direct and simple means of preparing various 
other compounds which can, by other methods, be obtained only 
with great difficulty or not at all. 
